A new fixed Twin-block appliance in the treatment of adolescent patients with skeletal Class Ⅱ malocclusion

doi:10.19439/j.sjos.2025.03.013

Abstract

Abstract: PURPOSE: To evaluate the clinical effect of a new fixed Twin-block on adolescent patients with skeletal ClassⅡ malocclusion. METHODS: Twenty-one patients aged 10-13 years with skeletal ClassⅡ malocclusion with mandibular retrusion were chosen for functional treatment using a new fixed Twin-block. Before and after treatment, panoramic and cephalometric films were taken, and the observation indexes were measured and recorded. RESULTS: There was no loosening or destruction of the appliance during treatment, the mean duration of treatment was (11.42±1.78) months. The position of the mandible(SNB), the length of the mandible (Co-Gn), nasolabial angle (Cm-Sn-UL), condylar sagittal position(Pcd-S), the lower labial protrusion distances (LL-SnPg') were significantly increased (P<0.05) after treatment, and the relative position of the maxilla and mandible (ANB), Y-axis angle(SGn/FH), the inclination of the maxillary incisors (U1/SN), and the depth of the mental-labial sulcus (Si-LLPg') reduced(P<0.05). Maxillary position(SNA), posterior mandibular position(S Vert-Co), mandibular length(Go'-Me), the mandibular incisor inclination (IMPA), and upper and lower mesial incisor angles(U1/L1), protrusion of the upper lip (UL-SnPg') were changed but without significant difference(P>0.05). The vertically orientated measurements of the vertical position of the lower dentition(Ll-MP), L6-MP, the vertical distance of the upper and posterior teeth (U6-PP), anterior height (N-Me), facial height index(S-Go'/N-Me), and mandibular plane angle (MP/SN) did not change significantly(P>0.05), while the posterior height(S-Go'), the vertical position of the upper dentition(U1-PP), occlusal plane angle (SN/OP), mandible height (Ar-Go'), the mandible ramus height(Co-Go) was increased significantly (P<0.05). CONCLUSIONS: New fixed Twin-block significantly promotes mandibular growth and provides effective vertical control, improves the facial profile by retracting the maxillary incisors, and the clinical effect is reliable.

Key words: New fixed Twin-block, Skeletal Class Ⅱ malocclusion, Functional orthodontic treatment, Vertical control

CLC Number:

R783.5

Ding Meng, Zhang Wei, Shen Qun, Chen Yucheng, Zhang Hui, Ge Feifan, Hang Mengyue, Wu Jianhua. A new fixed Twin-block appliance in the treatment of adolescent patients with skeletal Class Ⅱ malocclusion[J]. Shanghai Journal of Stomatology, 2025, 34(3): 291-297.

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